1. Field of the Invention
The present invention relates to a gate driver circuit generating an output signal for driving an insulated gate bipolar transistor (IGBT), and an operating method thereof.
2. Description of the Related Art
In a gate driver circuit controlling an operation of an insulated gate bipolar transistor (IGBT), when a plurality of IGBTs having different ratings are driven, a gate driver circuit appropriate for characteristics of the IGBTs is required in order to satisfy turning-on and turning-off speeds appropriate for ratings of the respective IGBTs. According to the related art, a method of inserting a resistor between an output terminal of the gate driver circuit and a gate terminal of the IGBT or controlling a size of a transistor connected to the output terminal of the gate driver circuit has been used in order to control the turning-on and turning-off speeds of the IGBT.
In the method of inserting the resistor between the output terminal of the gate driver circuit and the gate terminal of the IGBT to control an output current of the gate driver circuit, when rapid turning-on and turning-off speeds are required, the output current may be raised, and when slow turning-on and turning-off speeds are required, the output current may be lowered. In the method of controlling the size of the transistor connected to the output terminal of the gate driver circuit, in the case in which the size is increased, a source current is increased, such that turning-on and turning-off speeds may be increased, and in the case in which the size is decreased, turning-on and turning-off speeds may be decreased.
However, the above-mentioned two methods are not appropriate for controlling turning-on and turning-off speeds of the plurality of IGBTs having different ratings. In the first method, a circuit having several different resistance values is required in order to generate several output currents, and in the second method, it is required to connect a plurality of circuits having different sizes to one another in series. Therefore, in both of the first and second schemes, the size of the gate driver circuit is increased, and manufacturing costs are also increased.
In the Related Art Document below, Patent Document 1 relates to a semiconductor device and a data output method thereof and discloses a feature of providing a driving signal to certain transistors selected from among a plurality of transistors, and Patent Document 2 relates to a complementary metal oxide semiconductor (CMOS) output buffer circuit for controlling a driving current and discloses a feature of selectively transferring a control signal to an output buffer to control a level of an output current. However, neither of Patent Documents 1 and 2 discloses a feature of generating a control signal according to a connection state of each of a plurality of bonding pads and controlling turning-on/off of a switch device connected to an output terminal by using the generated control signal to control a level of an output current.